1. Field of Invention
The present invention relates to a measurement device. More particularly, the present invention relates to an ion current measurement device.
2. Description of Related Art
Before the ion related process, such as ion implantation process, is performed, it is usually to measure the ion current of the ion beam produced by the ion source to confirm the actual ion current amount of the later performed ion related process. Currently, the most used ion current measurement device is Faraday housing (as known as Faraday cup).
Since the ion current measurement device collects total ions of the ion beam from the ion source in a time period for further calculating the actual ion current, the ions (or ion beam) is blocked inside the ion current measurement device before the ions can reach the target. And the blocked ions (ion beam) produce gases and further induce residual coating inside the ion current measurement device. Moreover, the residual coating is aggressively accumulated inside the ion current measurement device after several times of ion related process are performed. Hence, the residual pilling problem happens.
Furthermore, because of the huge amount of phosphorous ion residual coating on the inner wall of the ion current measurement device, it is easily to fire the phosphorous ion residual during the cleaning process, such as vacuuming or polishing. Thus, the cleaning process for cleaning the inner wall of the ion current measurement device induces serious public security problem.